Triggering mechanism for needle-free injector

ABSTRACT

Needle-free hypodermic jet injection devices having an actuation system to effect an injection from a drug delivery system. The actuation system includes an injection force assembly adapted to transmit a driving force to the drug delivery system. The actuation system further includes a trigger assembly adapted to alter the actuation system between a plurality of configurations including a fired configuration in which the injection force assembly transmits a driving force to the drug delivery system. In some embodiments, the device has a recoil restriction system including a restriction member adapted to couple the recoil restriction system to the trigger assembly and a recoil member coupled to the injection force assembly and movable relative to the restriction member. The restriction member limits movement of the recoil member once the recoil member moves a predetermined distance relative to the restriction member.

BACKGROUND

Needle-free injection systems provide an alternative to standard fluiddelivery systems, which typically use a needle adapted to penetrate theouter surface of a target. Typically, needle-free injection systems aredesigned to eject the fluid from a fluid chamber with sufficientpressure to allow the fluid to penetrate the target to the desireddegree. For example, common applications for needle-free injectionsystems include delivering intradermal, subcutaneous, and intramuscularinjections into or through a recipient's skin. For each of theseapplications, the fluid must be ejected from the system with sufficientpressure to allow the fluid to penetrate the tough exterior dermallayers of the recipient's skin.

Examples of needle-free injection systems are found in U.S. Pat. Nos.4,940,460, 4,941,880, 5,399,163, 5,746,714, 5,782,802, 5,993,412,6,096,002, 6,132,395, 6,264,629, 6,383,168, 6,471,669, 6,572,581,6,585,685, 6,607,510, 6,641,554, 6,645,170, 6,648,850, 6,676,630,6,689,093, 6,752,781, and 6,783,509, the disclosures of which areincorporated herein by reference for all purposes.

Since needle-free injection systems require the production of high fluidpressures, recoil of injector components may limit device accuracy oreffectiveness. Various attempts have therefore been made to reducerecoil in injection systems. Examples of such devices are found in U.S.Pat. No. 5,957,886 and U.S. Patent Application Nos. 2004/0106895 and2005/0267403, the disclosures of which are incorporated herein byreference for all purposes.

SUMMARY

The present disclosure is directed to needle-free injection deviceshaving actuation systems to effect an injection. The devices have a drugdelivery system including a nozzle having a drug chamber and an outletorifice. The drug delivery system is adapted to expel a volume of liquidfrom the drug chamber through the outlet orifice at a sufficientpressure to penetrate a recipient's skin.

The devices also have an actuation system that includes an injectionforce assembly adapted to transmit a driving force to the drug deliverysystem. The actuation system further includes a trigger assembly adaptedto alter the actuation system between a plurality of configurationsincluding a fired configuration in which the injection force assemblytransmits a driving force to the drug delivery system. In someembodiments, the device has a recoil restriction system including arestriction member adapted to couple the recoil restriction system tothe trigger assembly and a recoil member coupled to the injection forceassembly and movable relative to the restriction member. The restrictionmember limits movement of the recoil member once the recoil member movesa predetermined distance relative to the restriction member.

The advantages of the disclosed needle-free injector may be understoodmore readily after a consideration of the drawings and the DetailedDescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exemplary device in a storedconfiguration in which a drug chamber is not in fluid communication withan outlet orifice of the device.

FIG. 2 is a cross-sectional view of the exemplary device of FIG. 1 in aprimed configuration in which the drug chamber is in fluid communicationwith the outlet orifice.

FIG. 3 is a cross-sectional view of the exemplary device of FIGS. 1 and2 in a fired configuration in which an injection force assemblytransmits a driving force to a drug delivery system to expel a drug fromthe drug chamber through the outlet orifice.

FIG. 4 is a fragmentary cross-sectional view of the exemplary device ofFIG. 1 showing details of a recoil restriction system and an actuationsystem that includes a trigger assembly and an injection force assembly.

FIG. 5 is a perspective view of an exemplary trigger assembly suitablefor the device of FIG. 4, including a retaining member, a recoil memberand a trigger sleeve.

FIG. 6 is a perspective view of the trigger assembly of FIG. 5 with thetrigger sleeve removed and the retaining member and recoil member in afired configuration.

FIG. 7 is an exploded view of the exemplary device of FIGS. 1-6.

DETAILED DESCRIPTION

FIGS. 1-7 illustrate exemplary needle-free injection devices 10.Although the disclosed devices are intended to be single-use, disposabledevices, various aspects of the devices may be incorporated intoreusable needle-free injectors.

Device 10 may include one or more systems to effect an injection. Forexample, the device of FIGS. 1-3 includes a drug delivery system 12, anactuation system 14, and a recoil restriction system 16. Drug deliverysystem 12 provides an interface for delivery of a drug to a recipientand expels a volume of liquid from the device. Actuation system 14provides a driving force to the drug delivery system. Recoil restrictionsystem 16 limits effects of recoil upon actuation, or firing, of thedevice.

Device 10 includes a body 20 to house the various systems. As shown inFIGS. 1-3, body 20 includes an outer housing 22 configured to houseactuation system 14 and recoil restriction system 16. The body is alsoconfigured to receive drug delivery system 12 for delivery of a drug orother fluid into a recipient. The outer housing may include a top 24 anda bottom 26 for ease of assembly of the device. Body 20 further includesa back cover 28, which is configured to move relative to outer housing22. Body 20 is typically configured to be comfortably held in a user'shand and may take any suitable configuration. Body 20 may be formed frominjection-molded plastic, though various other materials and fabricationmethods may be suitable.

Drug delivery system 12 is configured to expel a volume of fluid, suchas a drug, from the device. The word “drug” as used herein is intendedto encompass, for example, and without limitation, any medication,pharmaceutical, therapeutic, vaccine, or other material which can beadministered by injection. In a single-use configuration, the drugdelivery system may be permanently retained in, or coupled to, body 20prior to providing the device to a user; however, it should beappreciated that drug delivery system 12 may be selectively engageablewith the remainder of the device, such as for reusable devices.

Drug delivery system 12 includes a nozzle 30 in the form of a plasticsleeve 32. Nozzle 30 may be filled during operation of the device or mayinclude a pre-filled drug injection cartridge 34 placed within theplastic sleeve. As shown in the exemplary device of FIGS. 1-3, drugcartridge 34 includes a glass sleeve 36 which forms a drug chamber 38.The glass sleeve terminates adjacent an outlet valve 40 thatcommunicates with an end surface 42 of the nozzle 30 through an outletorifice 44. Outlet orifice 44 is shown in the form of a fine-dimensionopening from which issues a high velocity jet of medication uponactuation of the device.

In the exemplary device, drug delivery system 12 is coupled to actuationsystem 14. As illustrated in FIGS. 1-3, coupling threads 46, 48 join thenozzle and the actuation system. For single-use devices, these threadedsections may be joined prior to assembly of outer housing 22 to preventreuse of the device.

Although the depicted example illustrates a drug chamber having constantdiameter, the walls of the drug chamber may take the form of astepped-through bore having various diameters along the length of thecartridge, such as shown in U.S. Pat. No. 6,264,629. For example, theglass sleeve may be contoured to provide for variation in diameter.

Sealingly and movably received in drug chamber 38 is a resilient plunger50. The plunger may include multiple grooves 52 interdigitated withsealing ribs 54 that engage the walls of the drug chamber 38. Movementof plunger 50 urges fluid out of drug chamber 38 through outlet orifice44.

Outlet valve 40 is formed by a plug member 56 that moves from being heldby a drug cartridge seal 58 to a plug receiving chamber 60. As describedin U.S. Pat. No. 6,264,629, the disclosure of which is incorporated inits entirety, receiving chamber 60 may include one or more channelsthrough which fluid may bypass the plug member so that the drug chamberis in fluid communication with the outlet orifice once the plug memberhas moved into the receiving chamber. Alternatively, or additionally,plug member 56 may include ribs or slots, such as described in U.S. Pat.No. 6,132,395, to provide bypass channels for fluid communicationbetween the drug chamber and the outlet orifice.

Prior to its use to effect an injection, outlet orifice 44 of thepre-filled drug cartridge may be sealed by placing a peel-off type ofsealing membrane over end surface 42, which may be formed, for example,of foil or of a polymer/paper laminate as are conventional and wellknown in the art.

In some versions of the device, such as shown in FIGS. 1-3, outerhousing 22 includes a lip 62 to limit movement of the drug deliverysystem within the housing. For example, lip 62 may provide an end pointfor movement of the drug delivery system within the housing duringassembly of the device and firing of the device, such as upon recoil.

Actuation system 14 provides a driving force to the drug delivery systemand is alterable between a plurality of configurations. For example,actuation system 14 has a stored configuration in which the drug chamberis not in fluid communication with the outlet orifice, such as throughplacement of plug member 56 within cartridge seal 58, as shown inFIG. 1. FIG. 2 illustrates actuation system 14 in a primed configurationin which the drug chamber is in fluid communication with the outletorifice. As will later be described, movement of plunger 50 may urgeplug member 56 into receiving chamber 60 to allow fluid to bypass theplug member and thereby exit the drug chamber through the outlet valve.FIG. 3 illustrates the actuation system of an exemplary device in thefired configuration. In the fired configuration, a driving force istransmitted to the drug delivery system to effect an injection, such asby moving plunger 50 to urge the contents of the drug chamber throughthe outlet orifice.

To alter the actuation system between the plurality of configurations,device 10 includes a trigger assembly 70. Trigger assembly 70operatively couples actuation system 14 with drug delivery system 12.For example, trigger assembly 70 may control triggering of an injectionforce assembly 72, which transmits a driving force to the drug deliverysystem.

In the exemplary device of FIGS. 1-3, trigger assembly 70 comprises aninterior housing 74 that couples the actuation system with the drugdelivery system. In some versions of the device, interior housing 74includes selectively engageable first and second housings, such as aforward interior housing 76 and a rearward interior housing 78. Thehousings move selectively relative to one another to alter the actuationsystem between at least two of the plurality of configurations, such asfrom the stored configuration to the primed configuration. Asillustrated in FIGS. 1 and 2, housings 76, 78 include thread sections 80and 82, respectively, that engage one another and may be used to movethe forward and rearward interior housings relative to one another.

In the exemplary device of FIGS. 1-4, trigger assembly 70 includes atrigger sleeve 84 to limit relative movement between the forward andrearward interior housings. For example, the trigger sleeve may limitmovement between the housings so that alteration of the actuation systembetween the primed configuration and the stored configuration islimited. Trigger sleeve 84 may include protrusions 86, such as theangled ribs or ratchet teeth shown in the exemplary device of FIG. 5, tolimit relative movement between the housings in a predetermineddirection. As illustrated, the protrusions extend into the body, such asinto outer housing 22, and limit relative movement of the triggersleeve.

As illustrated in FIG. 5, trigger assembly 70 includes a retainingmember 90 to limit activation of the injection force assembly. Forexample, retaining member 90 may be configured to limit transmission ofa driving force when the actuation system is in the stored and primedconfigurations. Retaining member 90 may take the form of a back clip 92that includes apertures 94, at least some of which are configured toengage with interior housing 74.

Movement of trigger sleeve 84 may be coupled to interior housing 74 andretaining member 90. For example, trigger sleeve 84 includes channels 96configured to couple movement of the trigger sleeve with one of theinterior housings. As shown in FIG. 5, interior rearward housing 78includes flanges 100 that pass through apertures 94 in back clip 92.Protrusions 102 extend from the flanges to maintain engagement with backclip 92. The trigger sleeve maintains engagement with the rearwardinterior housing via channels 96 within the trigger sleeve, throughwhich the interior rearward housing translates. Between channels 96 arelips 104 that rest between the flanges of the rearward housing. Thetrigger sleeve therefore rotates in tandem with the rearward housing andback clip, but allows the rearward housing and back clip to translateindependently of the trigger sleeve. Although the components of triggerassembly 70, such as rearward housing flanges 100 and trigger sleevechannels 96 are shown in triplet, any suitable quantity andconfiguration may be used.

Trigger assembly 70 may be biased against firing of the device, such asby restricting movement of the actuation system to the firedconfiguration. For example, trigger assembly 70 may include a triggerspring 106 that maintains retaining member 90 away from back cover 28.In some versions of the device, the trigger spring may be tuned to matchthe magnitude of an axial force 108 of a predetermined value applied tothe end of the device, as shown in FIG. 2. Trigger spring 106 maytherefore counteract an initial contact force applied to the device asthe device is pressed against a recipient's skin. Consequently, apredetermined axial force is necessary to actuate the device to deliveran injection.

Injection force assembly 72 of actuation system 14 transmits a drivingforce to the drug delivery system. In the exemplary device of FIGS. 1-6,injection force assembly 72 includes a source of pressurized gas, suchas gas cartridge 110, to transmit a driving force to the drug deliverysystem. The injection force assembly includes a hammer member 112 toengage gas cartridge 110 with the drug delivery system by urging gascartridge 110 towards a pierce pin 114. Pierce pin 114 punctures apenetrable wall 116 of the gas cartridge to release the pressurized gas.In the exemplary device of FIGS. 1-7, device 10 uses pressurized gassupplied from a cartridge to expel fluid from the injection device.However, the pressurized gas may be supplied from a tank or othersource. In some versions of device 10, the driving force may be suppliedfrom one or more springs as is known in the art.

In the exemplary device of FIGS. 1-6, retaining member 90 includesextensions 118 ending in detents 120 adapted to releasably couple withinjection force assembly 72. For example, detents 120 may be configuredto releasably couple with hammer member 112, such as at hammer notches122. As shown in FIG. 4, the detents may take the form of one or moreshort, bended tips extending from the retaining member. The detents mayhave any angle relative to the extensions as is suitable for couplingwith the hammer member. A hammer spring 124 is positioned between theretaining member and the hammer member. When detents 120 disengage fromnotches 122, the hammer spring propels the hammer away from theretaining member to urge the gas cartridge towards the pierce pin.Consequently, the material from which the retaining member is formed andthe configuration of the detents may be selected to provide suitableresistance against application of an axial force to, and resultingactuation of, the device.

Gas chamber 126 is formed by forward housing 76. As illustrated in FIGS.1-3, a seal 128 is provided around rearward interior housing 78 so thatpressurized gas from cartridge 110 flows into gas chamber 126 instead ofescaping between the interior housings 76, 78. A seal 130 may also beprovided adjacent penetrable wall 116 to limit back flow of pressurizedgas into rearward housing 78. Located within the forward housing 76 is agas piston 132 which abuts plunger 50. As pressurized gas is releasedfrom cartridge 110, piston 132 is urged into nozzle 30. The plunger isconsequently urged along the drug chamber to effect an injection. A seal134 is provided with piston 132 to limit flow of pressurized gas out ofthe gas chamber until sufficient movement of the piston has occurred.For example, the interior walls of the rearward housing 78 may include aridged region near the nozzle to allow venting of excess gas past thepiston once the piston has moved to the end of the gas chamber oppositethe pierce pin. Gas chamber 126 may include a vent 138 to dissipateexcess pressurized gas. Additional vents may be provided in the outerhousing to release this exhaust gas or the exhaust gas may be redirectedfor use in a marking system, such as that described in U.S. Pat. No.6,676,630.

Recoil restriction system 16 limits effects of recoil once the device isfired, such as by limiting movement of the injection force assembly 72,such as backwards movement of the gas cartridge. Movement of theinjection force assembly relative to body 20 may be accomplished bycoupling the injection force assembly to the trigger assembly.Consequently, the recoil restriction system may limit movement of theinjection force assembly when the actuation system is in the firedconfiguration.

As illustrated in FIGS. 1-6, recoil restriction system 16 includes arecoil member 140 having a first end coupled to hammer member 112 and asecond end configured to engage with retaining member 90. The recoilrestriction system also includes a restriction member 142 to couple therecoil restriction system to trigger assembly 70. As shown in FIGS. 1-6,the recoil member is movable relative to the restriction member;however, the restriction member limits movement of the recoil memberonce the recoil member moves a predetermined distance relative to therestriction member.

In the exemplary device of FIGS. 1-7, restriction member 142 comprises abeveled edge 144 surrounding one of apertures 94 in retaining member 90through which the recoil member translates. Recoil member 140 comprisesan elongate tube 146 coupled to the hammer member and configured totranslate through the aperture 94 in the retaining member. In someversions of device 10, the recoil member includes flanges 148 extendingfrom tube 146 to engage with beveled edge 144. Consequently, once thedevice is fired, the hammer spring urges the hammer and the recoilmember away from the retaining member. The recoil member is movedcompletely through the aperture and is unable to move in the oppositedirection since flanges 148 catch on beveled edge 144.

In some versions of device 10, the device may provide feedback orinstructions to a user of the device. In the exemplary device of FIGS.1-3 and 7, the device includes view port 152 in outer housing 22. Theview port may be an aperture or window configured to allow a user toview a portion of an interior component, such as trigger sleeve 84,through the outer housing. For example, indicia, such as arrows or text,may instruct a user in proper operation of the device or conveyinformation to a user, such as whether the device is in the stored orprimed configuration.

Device 10 may include various mechanisms to restrict undesirablemovement of components. For example, in the illustrative device of FIG.7, outer housing 22 and interior forward housing 76 include one or moreribs 154, 156 that restrict rotation of the outer housing relative tothe interior forward housing. For example, outer housing top 24 and/orouter housing bottom 26 may include a pair of ribs that straddle one ormore ribs extending from interior forward housing 76. Other suitablemechanisms, such as latches, detents, glues, and the like, may be usedto restrict movement between these components and any other componentsdepending on the particular configuration of device 10.

During use, a user primes the device by rotating back cover 28 relativeto outer housing 22. As shown in FIGS. 1-4, the lower interior of backcover 28 engages back clip 92 adjacent extensions 118. The back clip 92,interior rearward housing 78, and trigger sleeve 84 therefore rotatewith the back cover to thread the rearward housing fully into theinterior forward housing 76. Protrusions 86 on trigger sleeve 84 preventback rotation. Threading of the interior rearward housing into theinterior forward housing moves gas piston 132 and plunger 50 towards theoutlet orifice to urge plug member 56 into its receiving chamber 60 sothat the bypass channels through the nozzle orifice allow fluid flow.

Once the device has been altered from the stored configuration, asdemonstrated by FIG. 1, to the primed configuration, as demonstrated byFIG. 2, the device is ready to be used to deliver an injection. The endsurface of the nozzle is placed against the skin of the person or animalwho is to receive the injection and an axial force is applied to thedevice, similar to that of the devices describe in U.S. Pat. Nos.6,096,002 and 6,264,629. The axial force causes the outer housing, backcover, and trigger sleeve to translate relative to the interiorcomponents. Accidental firing of the device is resisted by triggerspring 106. When the back cover contacts the end of recoil tube 146, therecoil tube urges hammer member 112 away from back clip 92, therebyreleasing detents 120 from the hammer. Hammer spring 124 urges thehammer away from the back clip and propels gas cartridge 110 onto piercepin 114, thereby moving the piston member and plunger through the drugchamber to effect the injection.

Although the present device has been shown and described with referenceto the foregoing operational principles and preferred embodiments, itwill be apparent to those skilled in the art that various changes inform and detail can be made without departing from the spirit and scopeof the invention. The present invention is intended to embrace all suchalternatives, modifications and variances. The subject matter of thepresent invention includes all novel and non-obvious combinations andsubcombinations of the various elements, features, functions and/orproperties disclosed herein. Inventions embodied in various combinationsand subcombinations of features, functions, elements, and/or propertiesmay be claimed through presentation of claims in a subsequentapplication.

1. A needle-free injection device comprising: a drug delivery systemincluding a nozzle having a drug chamber and an outlet orifice, the drugdelivery system adapted to expel a volume of liquid from the drugchamber through the outlet orifice; an actuation system including: aninjection force assembly adapted to transmit a driving force to the drugdelivery system; and a trigger assembly adapted to alter the actuationsystem between a plurality of configurations including a firedconfiguration in which the injection force assembly transmits a drivingforce to the drug delivery system; and a recoil restriction systemincluding a restriction member adapted to couple the recoil restrictionsystem to the trigger assembly, and a recoil member coupled to theinjection force assembly and movable relative to the restriction member,wherein the restriction member limits movement of the recoil member oncethe recoil member moves a predetermined distance relative to therestriction member.
 2. The device of claim 1, wherein the triggerassembly includes a retaining member adapted to limit activation of theinjection force assembly.
 3. The device of claim 2, wherein theretaining member includes detents adapted to releasably couple with theinjection force assembly.
 4. The device of claim 2, wherein therestriction member comprises a beveled edge surrounding an aperture inthe retaining member, and the recoil member comprises an elongate tubeadapted to pass through the aperture.
 5. The device of claim 4, whereinthe recoil member further comprises flanges extending from the elongatetube and adapted to engage with the beveled edge.
 6. The device of claim1, wherein the trigger assembly comprises first and second housingsadapted to move selectively relative to one another to alter theactuation system between at least two of the plurality ofconfigurations, and a trigger sleeve adapted to limit relative movementbetween the first and second housings.
 7. The device of claim 6, whereinthe trigger sleeve includes ratchet teeth adapted to limit relativemovement between the first and second housings in a predetermineddirection.